EDIT: I was able to restore my image occlusion cards by downloading my collection from anki web as cqg recommended; please ignore my original question in quotes below. I still have not been able to figure out what I need to edit or how in order to remedy the “front of this card is blank” error. The error directs to this page, which has not been helpful for me: "The front of this card is blank" / Card Appearance / Knowledge Base - AnkiMobile/AnkiWeb Support
I received an error message that said “The front of this card is blank.” In attempting to fix it, I tried to add/change the HTML text in the front template and accidentally deleted all of the text. Now all my image occlusion cards say “The front of this card is blank.”
How can I get my IO cards back to displaying correctly?